This invention relates in general to vehicle driveshaft assemblies containing a structure for reducing the amount of noise generating by the driveshaft during operation. In particular, this invention relates to an improved apparatus and method of installing such a noise reduction structure within a driveshaft tube of a vehicle driveshaft assembly.
Torque transmitting shafts are widely used for transferring rotational power between a source of rotational power and a rotatably driven mechanism. An example of a torque transmitting shaft is a driveshaft tube used in a vehicle driveshaft assembly. The driveshaft assembly transmits rotational power from a source, such as an engine, to a driven component, such as a pair of wheels. A typical vehicle driveshaft assembly includes a hollow cylindrical driveshaft tube having an end fitting secured to each end thereof. Usually, the end fittings are embodied as end yokes that are adapted to cooperate with respective universal joints. For example, a driveshaft assembly of this general type is often used to provide a rotatable driving connection between the output shaft of a vehicle transmission and an input shaft of an axle assembly for rotatably driving the vehicle wheels.
One problem encountered in driveshaft assemblies and other rotatable structures is that they tend to produce and transmit undesirable sounds during operation. It is known that all mechanical bodies have a natural resonant frequency at which they tend to vibrate when operated at certain rotational speeds. This natural resonant frequency is an inherent characteristic of the mechanical body and is based upon many factors, including its composition, size, and shape. In the context of vehicular driveshaft assemblies, the rotational velocity of the driveshaft tube can be operated at or near its natural resonant frequency (or one or more of the harmonics thereof) when the vehicle is in motion. When this occurs, the driveshaft tube may begin to vibrate, causing the generation of undesirable noise. Thus, it would be advantageous to deaden or reduce the sound produced by a vehicle driveshaft assembly in order to provide the passengers with a more quiet and comfortable ride.
Various attempts have been made to reduce the sounds generated by vehicle driveshaft tubes during operation. For example, it has been found to be desirable to dispose one or more noise reduction structures within the hollow driveshaft tube to absorb some of the noise generated during use. Known noise reduction structures have been manufactured from many materials, including cardboard, foam, and the like. Frequently, the noise reduction structure engages the inner surface of the driveshaft tube in a relatively light press-fit engagement to prevent it from moving therein during use, yet facilitating the installation thereof. In the past, the noise reduction structures have been installed within the driveshaft tubes by disposing the leading end thereof adjacent an open end of the driveshaft tube and applying a force to the trailing end thereof to push it through the open end and into driveshaft tube. This method has been found to be relatively slow and inefficient, particularly in the context of the relatively high volume production requirements associated with the manufacture of vehicles and vehicle components. This method has also been found to be difficult to implement when the ends of the driveshaft tube have a smaller diameter than the central portion thereof. Thus, it would be desirable to provide an improved method for quickly and easily installing a noise reduction structure within a driveshaft tube of a vehicular driveshaft assembly.